Control mechanism for gravimetric feeders



April 25, 1950 E. E. HARPER CONTROL MECHANISM FOR GRAVIMETRIC FEEDERS 2 Sheets-Sheet 1 Filed May 17, 1944 mr W 5 w M flTTORNEK April 25, 1950 E. E. HARPER CONTROL MECHANISM FOR GRAVIMETRIC FEEDERS 2 Sheets-Sheet 2 Filed May 17, 1944 INVENTOR. L /me/ E flame/ ATTOEA/EX Patented Apr.

STATES PATENT OFFICE.

Elmer Harper, -Monrovia, Ceiifi; EstherPardee Harper execntrix or said Elmer E. Harper, 'de' ceased Applicationm'ey '11, 1944, Serial No. 535,975

8 Giaims.

The present invention pertains to automatic iiiau'i 'g" apparatus of the type "operating to d r "d1 ciiarg'e pfedeterinined *or measured Lemme-ts v of "a "material fora giV e'n purpose, as is Quifedidr' exainiple i'n' thehandling of chemical 1', er "n Water purification operations, timar'yobjtbf the invention relatesto the .fprovis'iorl dines/e 1 coritrolnieans fo'r-the autoniatie frii'ds'ur 'g' "means "or this class of apparatus.

-A f afn'ntdl 'obje'ctof my "invention, thereis tod'eviseen improved material feeding eefiar ii's'm int'vhich is incorporateda-noveitype for insuring the feed or dis- "t'ly predetermined amounts of given periods of time as wen i 'suree'proper uniform-rate of theieediiig roughout eai'eh perio-d of operation. purpose"? here devised'a' novel control yconst -ctijoio"Whihoperates byme'ansof a peri- F dio'ftransferiof Weight'matter emiappiying the ferr'ed portions-6f such Weight hich-th tenal to be handldhasbee'n loaded ally 'loaiar'ied, and also "making further f this unbelencirigiection" for-the purpose" of ing' a prcipeitionete 'eorreet-ion i the feeddis'c'her'ge mte of-said material.

piefof'su' h construction I'prov-ide i. pparat'usin "which a'typ'epf WV-Eight teri'ai as granular orshotlike materiai is r ierr d ata givelf'ratejnnd theweight inf th'e successively iedwr transferred a-rn'ou-nts or rammar niateria'l is applied es a I I -r" in the unkisilencing 'off the soaies eohe 'nism n simultaneously-applied ascor- ;re'ctive raster Tor-proportionately" modifying the eed -'or'- -disc1'ierge r ate e: the -'prin1ary-*-materia1 is being ha-ndled.

s afurtiierobjeet of niy -invent'ien t'o proy de a control sipparatfus-of thecharaeter stated which"*is"eilsoadaptedfto-ioe embodied in 'theform 'of dependentfor'fselfcontejinedtype-oi con- "fripris'ing' ali the ewential eiem'ents-of ma erie' rfiodifieetionthereof. the foregoing general "objects in View the inventlonwvillnow be described in detail by referoe -to 'tt ie edeompanying" drawings illustrating ti' "f ms 'ase eparaws ror embodyingthe ntial features' of my improvements, "sitter which tr'ios fetures eiid coinbinaltions"deemed to be particularly novel and patentabie will .be

duly set forth and claimed.

in the drawings: Figure 1 'is a view in sectional elevation iidnsera-ting zind embodying the-present:improxzedcontro l system and representing a, section taken on theline l l of FigureZ;

Figure '2 is a transverse sectional elevation, representing a section taken on theviine i.2s2 of Figure- 1;

Figure 3 is a sectional plain v1ew:and:r.epresen'ts a s'e'et-io'n taken on -the:1ine 3-3 i of Figure 2 Figure '4 is :an enlarged :sectional detail .view of a. part of the shot-feeding mechanism;

Figur e =5 is =3, diagrammatic 'view illustrating a-modified form of the apparatus; and

Figure 6 is-an enlarged "plan ViJEW of the air "ehoke valve element.

-Referrmg now to the accompanying :drawings 0 in detail, the control miecnanism forming the subject 1713131781 of the pr-esent invention is 10f :a. "character designed to be embodied in the dorm of -21, control unit such as may be 'assemblediinre eatinet structure IB suitable for 1; mounting .in -c'fperative relation -t'0 -a scaies mechenism, as by -keing-niounted on a supporting rnen 'iber: 2 such 25 the-framework of escalesgend in such position as to fae-fiiteite t'ne 'connection 01" t'he vcontrol mechanism-'to' tiie beam l l of theiscales, as day -rneansof-=-asuitab1e ior m -of connecting link i I 5. In these 'respeetsthepresent-invention resembles -tiie su'bie'et -matter of :my Batent No-2 416 994, -dated March 7,4947, relating to controlameehanism 'de'sig-ned 130 function :in a manner very 5 similar to the con-trol operationof the construct'ion' herein described.

-'For--'thesu-pport of -the control mec'hanismiinr 1 side' the cebin'et 10, I provi dean angular ty-peiof bracket structure :5, the upper endzof' whichsis 40 formed With-abearing: structure i .7 forzfiaitnensverse'pivot Ja'er'or fulcrum-1B carrying a weight eontrol bea-m' t9. At one side of this fulcrumthe beam I 9 --is provided with: el'n a'djustable poisezor balancing weight 'zfl and ailso ztn adjustable-pivot 2| for the eonneoting link 1 5 ands-at the other side of its fulcrum l8 the beamds provided with a pivot-bar 22 or w pairof hanger arms- 23 supporting aibucketwzfi for*receivingitheshot-weight -meteria1- -2 5*when the'same is fed or 'di-soharged 5 "by the method aboutto be described.

At thef' top of the braeketl 6 is secured-another bracket elements Brier the fixed-support of amagazine- 01 contein'er fl for the storage of a suiiiply bfsslidshot-weighfimateriei 25. The'bbt- "tomof *this container is-p'1-'ovided -withsuitable bracket projections 34 for journaling a, shaft 36 carrying a shot feeding wheel 38 in such a position that a portion of the periphery of said wheel projects within an opening 40 in the container bottom, as illustrated in Figure 4. The periphery of the wheel 38 is provided with one or more rows of recesses or pockets i2each preferably of a size suitable for accommodating a single grain of the shot material 25.

The shaft 36 is provided with a pair of sprocket wheels one of which is driven by a chain it from one of a pair of sprocket wheels 38 on a speed changer device (of a type such as is shown in my Patent No. 2,219,040, dated October 22, 1940) the other sprocket Wheel 38 being driven by a chain 52 from a sprocket 5d actuated by a suitable motor 56. The motor and speed changer are conveniently mounted within the bracket structure I6, as shown in Figure l, the function of said speed changer device being to control the speed of rotation of the feed wheel 38 within any desired limits.

The other sprocket wheel 44 on the shaft 38 drives a sprocket chain 58 and sprocket wheel 69 which actuates a conventional counter device or register 62 which is mounted on top of the container 32 and is preferably of a type to register both batch readings 65 and also total or cumulative readings as indicated at B8.

The shot bucket 24 is closed with the exception of an upper discharge spout 68 and a shot receiving funnel 16, one end of which is shaped to embrace a portion of the periphery of the shot feed wheel 38, the remainder of the funnel being shaped as a chute I2 which is attached to the upper portion of the bucket and projects down into about the center of the bucket.

At the end of each cycle of operation, the bucket 24 is adapted to be swung, by means of a handle I4, upwardly into inverted position, as illustrated by the dotted lines in Figure 1, for the purpose of emptying the shot back into the container 32 through a top opening l5, said container being formed with a hopper-like extension I6 shaped to receive and enclose the top of the inverted bucket and thereby guard against the loss by spilling of any of the shot material as the latter pours out of the spout 68 and through the opening 15 back into the container 32.

Provision is also made to insure that the shot feeding operation is stopped during the time required for emptying the bucket 24, by means of a cam device '18 connected to one of the bucket arms 23, which cam device operates in the inverted position of the bucket to engage one end of a pivoted arm carrying a conventional cut-0ut switch 82 in an electric circuit t4 and operative to open the motor circuit and thus stop the drive to the feed wheel 38.

Various types of control mechanism and connections may be provided between the weight control beam and the feeding means (of the primary material) which will be responsive to the unbalancing action of said beam, and one preferred arrangement and construction may be briefly described as follows.

The control beam I9 may carry a pointer 86 operating along a suitable scale 8'! indicative of beam deflections; and this tip end of the control beam may be further provided with a suitable connection 88 to an arm 90 of a rocker valve of thin metal or the like, the body portion 92 of which is formed into inverted cup or hood shape for flatwise engagement (when in valve closing position) with the mouth of a thin-edged air orireceptacle.

flce element 94 mounted at the entrance to an air choke tube 96. A pin 98 secured to the center of the body portion 92 of the valve serves to maintain the same in approximately central position over the orifice 94, and a small mass Hit of weight material (such as solder) may be applied to the opposite side of said body from the arm 9% to insure bringing the center of gravity of the valve structure below said orifice and thereby obtain emcient automatic valve closing action on lowering movement of the connection 82': in response to the control operation of the beam i9. Preferably the arm 95 of the valve rests upon a nut Hi2 which is adjustably mounted upon said link connection 88, although a reverse arrangement of said valve and nut may be used, as hereinafter illustrated.

The air choke tube 96 communicates with a water jet device I04 included as part of a water supply line Hi5, and also with a flexible tube I06 which connects with a Sylphon type of bellows device Hi8 having an operative connection IIO with a suitable valve H2 or other equivalent feed regulating device adapted to control the discharge of the primary material which, in the present instance, is assumed to be a liquid contained in a receptacle II4 suspended by means of a supporting connection IIri from a pivotal point I it on the scale beam I4 and on the opposite side of the scale fulcrum I2ii from that havin the pivot point I22 where connection is made with the link i5 already referred to. '1 he bellows device tilt may be supported by a fixed frame or bracket i2 1 attached to said receptacle H4, as illustrated; and between this bracket and an adjustable nut I26 on the operating connection H8 is mounted a coil spring I25 ior the purpose of maintaining the valve I i2 normally in cioseol position, as regards any discharge of liquid from the This is the relationship corresponding to such a position or the valve 32 as will allow no more than a negligible or inoperative vacuum to be produced in the flexible tube H15 and the bellows device I08.

The arrangement of the valve 92 and its connection to the control beam I9 are such that a deflection of the beam in response to the shot feeding action will permit the valve 92 to settle into more nearly closed position, which has the effect of choking the flow of air through the tune 9e and to that extent resulting in more air being withdrawn from the tube I06 and bellows device Hit, and hence producing an openin movement of the valve I I2 to feed more of the liquid material i'rom the receptacle I i4. On the other hand, as the load on the scales, represented by said receptacle H4 and its contents, is decreased, due to said feeding and discharge of a portion of said contents, so that the beam is caused to swing in the opposite direction, the valve 552 will likewise undergo a reverse or lilting movement, tilting it upon the orifice 94 and to that extent opening said orifice and allowing more air to be admLted to the tube 96, with the efi'ect of diminishing the amount of air withdrawn from the tube We and bellows device, i. e., a diminishing vacuum action, which permits an automatic closing movement of the valve H2 to reduce or shut off the discharge of material from the receptacle I I4.

A stop bracket I30 may be adjustably supported by means of a screw I32 or the like, engagin a slot I33 in said bracket, in overhanging relation to the valve 92 and a sufficient distance therefrom for permitting all normal operative movements of the valve while preventing any casual displacementiof: theasame fromcitsi'positionionithe orifice element 94 (see Figure 1) In preparing the apparatus 1 for .operation,-.; a supply of granular or shotrmaterial25 .(which maybe plain leadxshotcor if preferred, steel or bronze balls) is. placed inthe storage container 32. The size-oi this shot-depends upon therequirements to be met :by. reach aapparatus l i for example, asize maywbe selectedand the-pivot LI 5 so adjusted that, say (Lshot (whengsupported in the bucket Zfilvvilloffset a weightechangelof 1- lb. in the receptacle l.l4,-'and-hench=each grain of shot will balance /iuo lbvinsaidreccptacle and the batch counter reading- 64 of thecounter device 62 will register a loss of weight from-said p ac e OI" /100- lb. for'eachvgrain of shot discharged by the shot feed wheel 38 into thebucket 24. From this it willbeseen -that:-the;principle of the operation is to provide :anappropriate number of weight units sufiicient ior counterbalancing the scale-load, and means successively applying the unbalancing' force of those weight units, at apredetermined and controlled rate, and to utilize the resultant unbalancing action in turn as the means -I"or the automatic regulation or control of the feedingrate of the material. In such anoperation the sensitiveness of the control action is limited only -by the sensitiveness of the control beam balance and the minuteness of the subdivision oi the load into weight control units asrepresentedbythe number of such units utilizedfor counterbalancing the load. As a matter -offact it maybe pointed. out that high grade scales are sensitive "to changes in weight; muchsmaller than provided for by the graduations on the limited length of scale beam;- and the improved-method of the present invention therefore, because of the minute subdivision of weights-used,- enables the range of operation to-be extended (even with present standard scales apparatus) to 'embrace and cover the requirements asto-verysensitive weighing, involved in the operation ofgravimetric feeders.

The receptacle H6 maybe suspended on a simple beam as shown, or may of course be-supported on hopper or platform-scalesof'any'capacity, and is balanced'empty by the tare -weight 38, the motor 55 meanwhilebeing idle and the shot bucket z l being entirely empty; Thus the entire system is initially iii-balance. The receptacle l M is-next filledand thesyStem-a'ebalanced by means of the poise 148 on" the scale bar M of the beam i l, and-the-said poise'then secured in this balanced-position (indicating the net Weight of the contents of the receptacle' l l l).

With the scale system in balance," and the water jet device I04 put in operation," the-aircontrol valve 92 willbe open Wide enough to admit sufficient air to prevent development ofa vacuum action in the connections to the bellows device its strong enough to operate the valve I12.

On starting the motor 56 the drive through the speedchanger 5s operates theshot '5 feed wheelie to discharge the shot: from the cone. tainer 32 into the bucket 24 at a known and controlled rate as determined by :theladjustment of said speed changer unit 50. The addition of this weightldue :totsaidflow of shot :ma-

terial) slightly unbalanceszthe :lcontrol beamand tends to lower its tip end and thus allowa settling of the air control ;valve- 92:.down into more nearly closed position uponrthe orifice 5t and to that'textent choke: the al1'2Ifi0W. th8lB- through and intensifyingnthei vacuum traction produced i in: connections to the bellows device. whichttransmits an opening movement to the valve 1 12. After a shortvinterval -oi operation a condition of equilibrium is established,- due to the.unbalancing action referred to being exactlyzofiset, or counterbalanced, by the rater-of discharge of the material from the receptacle H4; in other words, the control of the feeding actionthus produced is just to the required extent necessary for establishing a liquid discharge from the receptacle at a rate whi'ch will be in exact proportion to the rate at which-the shot is being discharged from the storage container 32 into the bucket 24; and in the establishment of this feeding rate the valve 92 is so adjusted by means of its nut 26 that in the normal operation of the control mechanism the control beam [9 will remain practically continuously in a horizontal position.

The'foregoing balancedoperation will continue until all the material has been discharged from the receptacle H4, and ifthe attendant doesnot interrupt the shot-feeding operation and refill said receptacle for' the starting of another cycle, the continued shot flow will unbalance the control beam sufiiciently to operate an'alarm circuit i 42 having a conventional switch device 5 15 located in position'for engagement by trip arms M1 and M3 carried by the control beam, as illustrated in Figure 1. This electric circuit may also, if desired, include safety relays or the like for shutting down the operation entirely; and faulty operation, such as interruption of the shot-feeding action or failure of either of the valves 92 or M2 to function properly, will quickly unbalance the system and thereby cause operation of the alarm, in a manner similar to that referred to in my aforesaid copending application.

The counter device 62 is manually reset at the beginning of each new cycle, so that the batch reading will register zero; and the gear drive from the shot feed wheel is arranged to produce counter readings in pounds and decimals thereof corresponding to the exact weight of material discharged from the receptacle H4 from the beginning of the cycle, the readin s 86 showing total or cumulative amounts in the usual manner.

A special advantage which characterizes the use of shot or granular material as the weight material required for the control Operation is the availability of such granular form of material in commercial quantities in very uniform sizes; as, for example, in ground balls of the type used in ball bearings and manufactured to very close tolerances. However, for a very Wide range of operationsl have found that ordinary: lead shot will function -.very satisfactorily and with sufficient accuracy for many purposes; for example, a size of shot averaging upwards of.-::seven thousandshot grains per pound is entirely-practical and' satisfactory for a' great many applications.

Another peculiar advantage attending theuse of the shot material is the fact that it promotes scale sensitivity due to the continual'slight jarring action imparted to the control system by the impact of the falling shot grains as they drop into the bucket; this has the effect or keeping-the scale system alive, as the expression goes, being comparable to the benefits aimed at in the use of vibratory mechanism in connection with scale'mechanism for-promoting a .i'reer and more sensitive scale action.

The useiofthe-special typeptaincontrolvalvc 7 92 in connection with the weight control beam is also particularly eifective for the required con trol function, due to its simplicity and being of so sensitive a type as to require only a negligible amount of force for its operation, and thereby imposing no objectionable load on the beam such as would materially obstruct its movements or operation. Moreover the design of said valve and its control connections is adapted for ready ad- J'ustment, and also for operation in either direction with the same result, thus rendering it suitable for different forms of installation.

It is also pointed out that other types of control mechanism and connections may be employed in lieu of said valve 92 and its connections to the feeding means, depending upon operating conditions and the character of materials to be handled, my Patents Nos. 2,080,267, 2,100,315 and 2,100,316 showing examples of such varying requirements and forms of mechanism suitable therefor.

One special advantage of the present type of control construction is its embodiment in the form of a control unit (as in my aforesaid prior patent) which can be constructed as a separate and independent or selfcontained assembly adapted to be quickly and conveniently attached as an accessory to practically any standard beam scale, without any change or redesign of the latter or interference with the ordinary normal use thereof, as required.

However, I have illustrated in Figure 5 of the drawings an alternative form of construction wherein the control beam as a separate element may be dispensed With altogether by combining the control feature in direct operative relation to the scale beam I l itself. Thus, the shot feeding means can be located in position for discharging the shot into the bucket 24 as suspended from a pivot 22' mounted on an extended portion of said beam 14'; and instead of the link i5, this can be replaced by a control link 88 connected to the valve 92 in such operative relation as to actuate the valve in the opposite direction from that already described, but causing the valve to carry out the same air control function, by its rocking movement upon the orifice 94, as will be readily understood. The fact that all driving mechanism, counter devices, etc., are mounted entirely independent of the control beam, in this modified form as well as in the previously described form of the apparatus, is also of especial advantage, in the interests of sensitivity of scale action, as well as simplicity of construction.

From the foregoing it will therefore be apparent that I have devised a highly practical form of construction and arrangement for fulfilling the desired objects of my invention; and while I have herein illustrated and described what I have found to represent very satisfactory and efficient forms of apparatus, etc., for embodying my improvements, I desire to be understood as expressly reserving the right to make whatever changes or modifications may fairly be deemed to fall within the spirit and scope of my invention as defined by the appended claims.

Having described my invention, what I claim is:

1. Apparatus for the gravimetric feeding of material'comprising, in combination with scales mechanism, a container for the material supported in balanced relation on said scales mechanism, feeding means for effecting discharge of material from said container, and a control structure comprising a balanced control beam 8 connected with said scales mechanism, a weight container supported by said control beam, means for discharging into said container a serie of separate and substantially equal weight units for imposing a, continuous succession of additive unbalancing impulses on said scales mechanism at a predetermined and controlled rate, and means actuated by movements of said control beam for transmitting coordinative impulses regulative of thefeeding means for offsetting said unbalancing eifect on the scales mechanism.

2. Apparatus for the gravimetric feeding of material comprising, in combination with scales mechanism, a container for the material supported in balanced relation on said scales mechanism, feeding means for effecting discharge of material from said container, and a control structure comprising a balanced control beam connected with said scales mechanism, a weight container supported by said control beam, an independently supported supply of homogeneous granular material comprised of separate and substantially equal weight particles, means for progressively discharging said granular material into said weight container for imposing a continuous succession of additive unbalancing impulses on said scales mechanism at a predetermined and controlled rate, and means responsive to movements of said control beam for imparting coordinate impulses regulative of the feeding means to offset said unbalancing effect on the scales mechanism.

3. Apparatus for the gravimetric feeding of material comprising, in combination with scales l mechanism, a container for the material supported in balanced relation on said scales mechanism, feeding means for effecting discharge of material from said container, and. a control structure comprising a balanced control beam connected with said scales mechanism, a weight container movably supported by said control beam, an independently supported supply of homogeneous granular weight material, means operating at a predetermined and controlled rate for progressively feeding separate weight particles from said supply of granular material into said weight container and thereby imposing a continuous succession of additive unbalancing impulses on said scales mechanism, and means actuated by movements of said control beam for transmitting coordinate impulses regulative of said first feeding means to offset said unbalancing effect on said scales mechanism, said weight container being movable into position for dumping its contents back into said supply of granular material.

4. Apparatus for the gravimetric feeding of material comprising, in combination with scales mechanism, a receptacle for the supply of material supported in balanced relation to said scales mechanism, feeding means for discharging material from said receptacle, and a control structure comprising a balanced control beam connected with said scales mechanism, a weight container supported by said control beam, an independently supported supply of weight material mounted in discharge relation to said container, means for progressively feeding said weight material into said container for imposing a continuous succession of additive unbalancing impules on said scales mechanism at a predetermined and controlled rate, means acting in unison with the operation of said last mentioned means for correspondingly regulating the operation of said first feeding means to offset.

said unbalancing effect on the scales mechanism, said weight container being movable into position for dumping its contents back into said receptacle, and means operating in the dumping position of said container for interrupting the operation of said weight material feeding means.

5. A selfcontained control unit for automatically controlling the operation of gravimetric feeding devices comprising, a balanced control beam having adjustable means of connection with the feedng device, means operating at a given controlled rate for progressively loading said control beam at a single point with a series of separate and substantially equa1 weight units for transmitting through said connection a succession of additive unbalancing impulses to the scales mechanism of the gravimetric feeding device, and connections responsive to movements of said control beam and operative to impart corresponding regulating movements to the material feeding means of the gravimetric feeding device.

6. Apparatus for the gravimetric feeding of material comprising, in combination with scales mechanism, a container for material supported in balanced relation to said scales mechanism, feeding means for effecting discharge of material from said container, and a control structure comprising a balanced control beam connected with said scales mechanism, means for applying the successive impacts of falling mass particles of uniform average Weight for imposing a continuous succession of additive unbalancing impulses on said scales mechanism at a predetermined and controlled rate, and means responsive to movements of said control beam for correspondingly regulating the operation of said feeding means and thereby preserving the balance of said scales mechanism.

7. Apparatus for the gravimetric feeding of material comprising, in combination with scales mechanism, a container for the material supported in balanced relation to said scales mechanism, feeding means for effecting discharge of material from said container, and a control structure comprising a balanced control beam connected with said scales mechanism and actuated by the fluctuations thereof, means for applying to said control beam a continuous succession of combined weight increments and jarring impulses operative to produce unbalancing movement of said control beam at a predetermined and controlled rate, and means responsive to movements of said control beam for correspondingly regulating the operation of said feeding means and thereby preserving the balance of said scales mechanism.

8. Apparatus for the gravimetric feeding of material comprising, in combination with scales mechanism, a container for material supported in balanced relation to said scales mechanism, feeding means for effecting discharge of material from said container, and a control structure comprising a balanced control beam connected with said scales mechanism, means for applying the successive impacts of falling mass particles for imposing a continuous succession of additive unbalancing impulses on said scales mechanism at a predetermined and controlled rate, and means responsive to movements of said control beam for correspondingly regulating the operation of said feeding means and thereby preserving the balance of said scales mechanism.

ELMER E. HARPER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,983,093 Montgomery Dec. 4, 1934 2,047,203 Henson July 14, 1936 2,416,994 Harper Mar. 4, 1947 

